- An experimental treatment for metastatic melanoma involves cell therapy, in which researchers take white blood cells (lymphocytes) from the tumor tissue, grow them in the laboratory in large numbers, and then use the cells to attack the tumor tissue. Before receiving the cells, chemotherapy is needed to temporarily suppress the immune system to improve the chances that the tumor-fighting cells will be able to survive in the body. In some studies of cell therapy, individuals who have received total body irradiation (TBI) in addition to the chemotherapy (in order to increase the length of time that they do not produce white blood cells) seem to have a slightly better response to the treatment, but it is not known if adding radiation to the cell therapy will cause a better response for all individuals. Researchers are interested in comparing cell therapy given with the usual chemotherapy to cell therapy given with the usual chemotherapy and TBI.